Apparatus and methods for using high frequency chokes in a substrate deposition apparatus

ABSTRACT

In certain aspects, a substrate deposition apparatus, including a gas tube coupled to a gas source, an RF power source and a substrate processing chamber, is provided. The gas tube is adapted to carry process gas and cleaning plasma from the gas source/remote plasma gas source to the substrate processing chamber and the RF power source is adapted to couple RF power to the substrate processing chamber. Furthermore an RF choke coupled to the RF power source and the gas source wherein the RF choke is adapted to attenuate a voltage difference between the RF power source and the gas source to prevent plasma formation in the gas tube during substrate processing. Numerous other aspects are provided.

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 60/714,723 filed Sep. 6, 2005 and entitled“APPARATUS AND METHODS FOR AN RF CHOKE” which is hereby incorporated byreference herein for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to high or radio frequency (RF)chokes and specifically to RF chokes for plasma processing chambers.

BACKGROUND

With each successive technology generation, substrate processingchambers may increase in size to accommodate larger substrates. Largersubstrate processing chambers may require an increase in the RF powerused to perform a substrate plasma process in the substrate processingchamber. What is needed are improved methods and apparatus that allowexisting processing chambers to be cost effectively enhanced to supportprocessing operations that use higher RF powers.

SUMMARY OF THE INVENTION

The invention provides a substrate deposition apparatus, comprising agas tube coupled to a gas source, an RF power source and a substrateprocessing chamber. The gas tube is adapted to carry gas from the gassource to the substrate processing chamber, and the RF power source isadapted to couple RF power to the substrate processing chamber.Furthermore, an RF choke is coupled to the RF power source and the gassource wherein the RF choke is adapted to attenuate a voltage differencebetween the RF power source and the gas source.

Other features and aspects of the present invention will become morefully apparent from the following detailed description, the appendedclaims, and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram depicting a substrate processing apparatusin accordance a first embodiment of the present invention.

FIG. 2 is a perspective diagram depicting the RF choke of FIG. 1 inaccordance with the first embodiment of the present invention.

FIG. 3 is a schematic diagram depicting a substrate processing apparatusin accordance with a second embodiment of the present invention.

FIG. 4 is a perspective diagram depicting the RF choke of FIG, 3 inaccordance with a second embodiment of the invention.

FIG. 5 is a perspective view of a top portion of a substrate processingapparatus in accordance with a third embodiment of the presentinvention.

FIGS. 6A, 6B, 6C and 6D are perspective, side, end, and detail views,respectively, of an RF choke in accordance with a third embodiment ofthe invention.

DETAILED DESCRIPTION

Substrate processing chambers may be adapted to perform a cleaningprocess using a remotely generated “cleaning” plasma that is deliveredto the chamber via the same channel that is used for delivering theregular process gases to the chamber. Thus, the cleaning process may usea cleaning plasma tube, which may be coupled to an RF power source,external to the substrate processing chamber. Accordingly, an RF powersource may be coupled to both the substrate plasma processing chamberand the cleaning plasma tube. The cleaning plasma tube may be coupled toa gas source and the RF power source. However, this may lead toundesired electrical coupling of the RF power source to the gas deliverydevice. To avoid this according to the present invention, a device maybe employed to electrically decouple or attenuate the voltage differencebetween the RF power and the gas source. This may be accomplished byplacing a device such as a dielectric gas tube (e.g., ceramic plasmatube) between the RF power source and the gas delivery device that mayalso serve as the cleaning plasma tube. However, this may result in alocalized high density electrical field, due to non uniform attenuationof the voltage difference between the gas source and the RF powersource, which may cause unintended plasma in the shared dielectric gastube/cleaning plasma tube during substrate processing.

A more uniform attenuation of the voltage may allow relatively higher RFpower to be delivered to the substrate processing chamber before plasmais ignited in the plasma tube. In other words, the present invention maybe used to prevent process plasma from forming in the cleaning plasmatube during substrate processing using higher RF powers. A resistor maybe placed between RF power source and the gas delivery apparatus and mayensure an approximately uniform attenuation of voltage differencebetween the RF power source and the gas delivery system. However, theresistor may be expensive, susceptible to damage and take up anundesired amount of volume. Therefore, there may be a desire for aninexpensive, compact apparatus adapted to ensure an approximatelyuniform attenuation of the voltage from the RF power source and the gasdelivery apparatus.

In accordance with the present invention, an RF choke is provided. In afirst embodiment, the RF choke may include a wire wrapped around ahollow plastic core or form. The plastic core may include groovesmachined into the surface so as to allow the wire to form a coiltraversing the length of the plastic core. Alternatively, in a secondembodiment of the RF choke, a wire with a dielectric coating may beprovided. The pitch between the wires may be established by thethickness of the dielectric coating on the conductive portion of thewire when the wire may be wrapped around an object such as a form or atube.

The RF choke may be electrically coupled to a gas source, an RF powersource and a substrate processing chamber. The coupling of the RF choke,or specifically, the coiled wire to the RF power source and the gassource, may induce a voltage drop along the length of the wire. Byproviding a wire wrapped into a coil, in accordance with the first twoembodiments, an approximately uniform voltage drop along the length ofthe wire may be realized. Thereby, the voltage drop that induces plasmain the substrate processing chamber and/or gas tube may be realizedand/or repeatable. These aspects of the invention are discussed below.

FIG. 1 is a schematic drawing depicting a substrate processing apparatus100 in accordance a first embodiment of the present invention. Thesubstrate processing apparatus 100 (e.g., embodied as Plasma ChamberModels 15K, 20K, 25K and/or 25KA manufactured by AKT, Inc. of SantaClara, Calif.) may include an inventive RF choke 102 disposed coaxiallyaround a gas tube 104. The gas tube 104 (e.g., formed from ceramic,quartz, and/or the like) may be coupled to a gas source 106 (e.g., a gaspanel, gas lines, and/or the like) via a gas delivery device 108 (e.g.,stainless steel gas line, gas distribution block, and/or the like).Furthermore, the gas tube 104 may be coupled to the substrate processingchamber 110 via a chamber distribution device 112 (e.g., stainless steeltubing, machined copper block, shower head, and/or the like). The RFchoke 102, which may be disposed coaxially around the gas tube 104, maybe electrically coupled to the gas delivery device 108. As previouslydiscussed, the gas delivery device 108 may be coupled to the gas source106. In addition, the RF choke 102 may be coupled to the RF power source114 (e.g., RF generator and matching network, variable frequencynetwork, and/or the like) via an RF delivery device 116 (e.g., a coaxialcable, bus bar, and/or the like).

With reference to FIG. 1, during a substrate fabrication process in thesubstrate processing apparatus 100, the RF power source 114 may coupleRF power to both the RF choke 102 and/or the substrate processingchamber 110. Furthermore, the gas source 106 may provide process gasesto the substrate processing chamber 110 via the gas delivery device 108,gas tube 104 and/or chamber distribution device 112. In this manner,plasma may be formed in the substrate processing chamber 110 and/or gastube 104.

Still with reference to FIG. 1, plasma may be formed in the substrateprocessing chamber 110 by flowing gas and coupling RF power to thechamber distribution device 112. The plasma may be employed to performmaterial removal and/or deposition processes (e.g., CVD, etch and/or thelike) on the substrate. During the material removal and/or depositionprocesses, the voltage level of the chamber distribution device 112(Vbs) may be known and/or repeatable so as to induce plasma in thesubstrate processing chamber 110 without forming plasma in the gas tube104.

Alternatively, there may be a need to perform a clean process in thesubstrate processing chamber 110. The clean process may be performed byflowing cleaning plasma gas to the gas tube 104 via the gas deliverydevice 108 (e.g., remote plasma clean source). During the flow of thecleaning plasma gas, the RF power source 114 may couple RF power to theRF choke 102 via the RF delivery device 116. In this manner, plasma maybe maintained in the gas tube 104. Furthermore, the voltage level of thechamber distribution device 112 (Vbt) that induces plasma in the gastube 104 may be known. The plasma may provide reactive species suchchlorine which may flow to the substrate processing chamber 110 via thechamber distribution device 112 to perform the clean process.

Still with reference to FIG. 1, plasma in the gas tube 104 may bemaintained in a known and/or repeatable manner by controlling thedistribution of the voltage along the length of the RF choke 102. Forexample, by having an approximately uniform distribution of voltagealong the length of the RF choke 102, the RF power output by the RFpower source 114 that may maintain plasma (and/or in some embodiments,induce plasma or prevent reactive species from recombining into a morestable state) in the gas tube 104 may be determined and thereby be morepredictable and/or repeatable. Additionally, different gas compositionsflowed from the remote plasma gas source 106 to the gas tube 104 mayform plasma at different Vbt voltage levels. Thus, for a variety of gascompositions, the voltage level Vbt that may induce plasma in the gastube 104 may be known and/or repeatable.

FIG. 2 is a perspective drawing depicting the RF choke 102 in accordancethe first embodiment of the present invention. The RF choke 102 mayinclude a core 200 (e.g., hollow plastic cylinder or the like) a coiledwire 202 (e.g., 17 AWG nickel-chromium or the like), a gas end bolt 204(e.g., stainless steel threaded bolt or the like) and a RF end bolt 206(e.g., stainless steel threaded bolt or the like).

With reference to FIG. 2, the core 200 may be disposed internal to theapproximately cylindrical geometry formed by the coiled wire 202 andserve as a form to support the coiled wire 202. Furthermore, the core200 may include a continuous groove 208 on the surface in which thecoiled wire 202 may be disposed to maintain the position of the wire andprevent short circuiting of coils. On a first end of the core 200 thegas end bolt 204 may be coupled to both the coiled wire 202 and the core200. A portion of the gas end bolt 204 may protrude from a first end ofthe core 200. Additionally, the RF end bolt 206 may be coupled to boththe coiled wire 202 and the core 200. A portion of the RF end bolt 206may protrude from a second end of the core 200. The coiled wire 202 maybe coupled to the RF delivery device 116 via the RF end bolt 206. Inaddition, the coiled wire 202 may also be coupled to the gas deliverydevice 108 via the gas end bolt 204.

Still with reference to FIG. 2, during the substrate and/or cleanprocess the RF end bolt 206 may be electrically excited to a voltage,Vbs and/or Vbt or any other suitable voltage, by the RF power source114. In addition, the gas end bolt 204 may be at or near earth groundvoltage (e.g., near zero voltage or the like). Thus, the coiled wire 202may have a voltage drop along the length of the wire that isapproximately equal to Vbs and/or Vbt or any other suitable voltage.Furthermore, the voltage drop along the length of the coiled wire 202may be approximately uniform. By having an approximately uniform voltagedrop that may be approximately equal to Vbs and/or Vbt or any othersuitable voltage, the RF power output from the RF power source 114 whichmay maintain (or induce ignition of) the plasma in the gas tube 104and/or substrate processing chamber 110 may be approximately determinedand/or repeatable.

FIG. 3 is a schematic drawing depicting a substrate processing apparatus300 in accordance a second embodiment of the present invention. Thesubstrate processing apparatus 300 may include an insulated RF choke 302disposed around the gas tube 104. The gas tube 104 may be coupled to thegas source 106 via a gas delivery device 108. Furthermore, the gas tube104 may be coupled to the substrate processing chamber 110 via a chamberdistribution device 112. The insulated RF choke 302, which may bedisposed around the gas tube 104, may be electrically coupled to the gasdelivery device 108. As previously discussed, the gas delivery device108 may be coupled to the gas source 106. In addition, the insulated RFchoke 302 may be coupled to the RF power source 114 (e.g., RF generatorand matching network, variable frequency network, and etc.) via a RFdelivery device 116 (e.g., coaxial cable, bus bar and etc.)

FIG. 4 is a perspective drawing depicting an RF choke 302 in accordancewith a second embodiment of the invention. The insulated RF choke 302may include an insulated coiled wire 304, the gas end bolt 204 and theRF end bolt 206. The gas end bolt 204 may couple the insulated RF choke302 to the gas delivery device 108. Furthermore, the RF end bolt 206 maycouple the insulated RF choke 302 to the chamber distribution device112.

Similar to the first embodiment in operation, during the substrateand/or clean process, the RF end bolt 206 may be electrically excited toa voltage by the RF power source 114. In addition, the gas end bolt 204may be at a voltage level near earth ground. Thus, the insulated coiledwire 304 may have a voltage drop along the length of the wire that isapproximately equal to voltage Vbs and/or Vbt or any other suitablevoltage. Furthermore, the voltage drop along the length of the insulatedcoiled wire 304 may be approximately uniform. In this manner, the RFpower output from the RF power source 114 which may induce ignition ofthe plasma in the gas tube 104 may be approximately known and/orrepeatable.

Turning to FIG. 5, a lid 502 of a processing chamber is depictedincluding a remote cleaning plasma source 504 in fluid communicationwith a diffuser 506 (leading into the processing chamber) via a gas tube508 surrounded by an RF choke 510. The lid 502 may be employed to coupleenergy (e.g., RF, microwave, etc.) to a fluid and distributing the fluidto the processing chamber. The gas tube 508 may be coupled to thediffuser 506 via a gas input 512. A matching network 514 may be coupledto the RF choke 510 and the lid 502. A grounded connector 516 may couplethe remote cleaning plasma source 504 and the RF choke 510 to electricalground (e.g., approximately zero volts).

With reference to FIG. 5, the remote cleaning plasma source 504 mayprovide a fluid. The fluid may be employed in the processing chamber toprocess substrates, clean the chamber, or any other suitable purpose.The fluid may be fluid (e.g., gas, vaporized water, etc.) or any otherfluid suitable for use in the processing chamber. Additionally oralternatively, the fluid may be ionized (e.g., into a plasma) orimparted other similar characteristics so as to perform the processes inthe processing chamber. The remote cleaning plasma source 504 maycomprise aluminum and/or any material suitable to provide the fluid. Forexample, in the same or alternative embodiments, portions of the remotecleaning plasma source 504 may include ceramic parts to ensure thatenergy (e.g., electrical) is not exchanged between the fluid and thelid.

The remote cleaning plasma source 504 may be adapted to provide a fluidfor processing. For example, the remote cleaning plasma source 504 maybe adapted to vaporize water to form gaseous water (e.g., steam). Suchfluid may be employed by the processing chamber.

The diffuser 506 may comprise anodized aluminum although any suitablematerial may be employed to distribute the fluid. As depicted in FIG. 5,the diffuser 506 may have a flat circular shape although any suitableshape and/or configurations of shapes may be employed. The diffuser 506may also have holes adapted to pass the fluid to the processing chamber.As discussed above the diffuser 506 may be in fluid communication withthe remote cleaning plasma source 504 via the gas tube 508.

The diffuser 506 may be employed to distribute the fluid in a desiredmanner. For example, it may be desired to distribute the fluid evenlyinside the processing chamber to ensure uniform processing.Alternatively, the diffuser 506 may distribute the fluid in anon-uniform manner to ensure that the fluid concentrates in desiredregions of the processing chamber.

As depicted in FIG. 5, the gas tube 508 may be a single circular tube508 although any suitable shapes and/or configuration of shapes may beemployed. The gas tube 508 may comprise anodized aluminum although anysuitable material or combination of materials may be employed.

The gas tube 508 may be adapted to convey the fluid from the remotecleaning plasma source 504 to the diffuser 506. The gas tube 508 mayalso insulate (e.g., electrically) the fluid from electrical or otherenergy sources. By insulating the fluid from the energy sources, the gastube 508 may ensure that a desired amount of energy is coupled to thefluid. In addition or alternatively, the gas tube 508 may be adapted tohold other components of the present invention. For example, as will bediscussed below, the gas tube 508 may be adapted to mechanically supportother components of the present invention.

Still with reference to FIG. 5, the RF choke 510 may be disposed aroundthe gas tube 508. The RF choke 510 is depicted as a single coil disposedaround the gas tube 508 although other suitable configurations may beemployed. Similar to the embodiment described above with reference toFIGS. 1-4, the RF choke 510 may be employed to couple energy to thefluid being conveyed by the gas tube 508. The gas input 512 may comprisealuminum although any suitable material may be employed. The gas input512 is depicted in FIG. 5 as a cube shaped although any suitable shapemay be employed. The gas input 512 may be adapted to couple the gas tube508 to the diffuser 506. The gas input 512 may be employed to convey thefluid from the gas tube 508 to the diffuser 506. In the same oralternative embodiments, the gas input 512 may be employed toelectrically insulate the diffuser 506 from the gas tube 508.

The matching network 514 may be coupled to the RF choke 510 and the lid502. The matching network 514 may include other components that are notdiscussed in detail in this application. The components may be inductorsand/or capacitors although other suitable components may be employed.The external shell of the matching network 514 may be aluminum althoughany suitable material may be employed.

The matching network 514 may be adapted to couple a source (e.g.,electrical) to the lid 502 via the choke 510. The matching network 514may be employed to match the electrical load presented to the matchingnetwork 514 (e.g., electrical load of the processing chamber, RF choke,etc.) to the load of the source. In the same or alternative embodiments,the matching network 514 may couple energy to the processing chamber viathe RF choke 510.

The grounded connector 516 may comprise aluminum although any suitablematerial may be employed. The grounded connector 516 is depicted in FIG.5 as a cube shaped device although any suitable shape may be employed.The grounded connector 516 may be adapted to couple an end of the RFchoke 510 to ground. In the same or alternative embodiments, thegrounded connector 516 may also be coupled to the remote cleaning plasmasource 504. By coupling an end of the RF choke 510 to ground, the energybeing coupled to the RF choke 510 via the matching network 514 may becoupled to ground through the RF choke.

FIG. 6A depicts a perspective view of an RF choke form 602 adapted toreceive and support a conductive coil 604 (which is partially shownwrapped about the form) coaxially about the gas tube 508 of FIG. 5.FIGS. 6B and 6C depict side and end views of the form of FIG. 6A. FIG.6D depicts a close-up detail view of grooves milled into the surface ofthe form to space and insulate the conductive coils from each other.Note that the drawings are not to scale and the dimensions may beadjusted to accommodate different sized chambers that use differentamounts of RF power. For example, the Plasma Chamber Model 40Kmanufactured by AKT, Inc. may use a longer RF choke than the Model 25Kor 15K mentioned above.

The RF choke form 602 may comprise a plastic such as polyamide althoughany suitable material may be employed. For example, the RF choke form602 may comprise a ceramic material in addition to other materials. TheRF choke form 602 may be adapted to receive and support the conductivecoil 604, as will be described below with reference to FIGS. 6B and 6D.

With reference to FIG. 6B, the RF choke form 602 may have the conductivecoil 604 wrapped around the external surface 606 of the RF choke form602. Note that the conductive coil may comprise a continuous wirewrapped around the RF choke form 602. In the same or alternativeembodiments, it may be desired to control the space between each loop ofthe wire. Accordingly, the RF choke form 602 may be adapted to controlthe space, as will be described below.

With reference to FIG. 6D, the RF choke form 602 may be adapted toreceive and hold the conductive coil 604 with a groove 608 in theexternal surface 606 of the RF choke form 602. The conductive coil 604may be disposed in the grooves 608.

Although the groove 608 is depicted as u-shaped valleys, any suitableshape may be employed. For example, in an alternative embodiment, thegroove 608 may be v-shaped or rectangular shaped. The groove 608 may beany suitable depth suitable for controlling the depth of the wire of theconductive coil 604 in the groove 608. Also, as depicted in FIG. 6D, thegroove 608 is a continuous feature along the length of the RF choke form602. In alternative embodiments, the groove 608 may comprise a pluralityof features.

The foregoing description discloses only exemplary embodiments of theinvention. Modifications of the above disclosed apparatus and methodwhich fall within the scope of the invention will be readily apparent tothose of ordinary skill in the art. Accordingly, while the presentinvention has been disclosed in connection with exemplary embodimentsthereof, it should be understood that other embodiments may fall withinthe spirit and scope of the invention, as defined by the followingclaims.

1. A substrate deposition apparatus, comprising: a gas tube coupled to agas source, an RF power source and a substrate processing chamber,wherein the gas tube is adapted to carry gas from the gas source to thesubstrate processing chamber, and wherein the RF power source is adaptedto couple RF power to the substrate processing chamber; and an RF chokecoupled to the RF power source and the gas source, wherein the RF chokeis adapted to attenuate a voltage difference between the RF power sourceand the gas source.
 2. The apparatus of claim 1, wherein the gas tube isdisposed within the RF choke.
 3. The apparatus of claim 1, wherein theRF choke includes a wire wrapped into a coil.
 4. The apparatus of claim3, wherein the RF choke further includes a core disposed inside the wirewrapped into a coil.
 5. The apparatus of claim 4, wherein the core isadapted to ensure the pitch of the coil is substantially constant. 6.The apparatus of claim 3, wherein the wire is coated with a dielectricmaterial.
 7. The apparatus of claim 6, wherein the RF choke furtherincludes a core disposed inside the wire wrapped into a coil.
 8. Theapparatus of claim 1, wherein the gas tube includes a dielectricmaterial.
 9. The apparatus of claim 8, wherein the RF choke includes awire wrapped into a coil.
 10. The apparatus of claim 9, wherein the RFchoke further includes a core disposed inside the wire wrapped into acoil.
 11. The apparatus of claim 10, wherein the core is adapted toensure the pitch of the coil is substantially constant.
 12. Theapparatus of claim 3, wherein the wire is coated with a dielectricmaterial.
 13. The apparatus of claim 12, wherein the gas tube isdisposed inside the coil.
 14. The apparatus of claim 1, wherein the RFchoke is further adapted to approximately uniformly attenuate thevoltage difference between the RF power source and the gas deliverysystem.
 15. A method, comprising: providing a gas tube, a gas source, anRF power source and a substrate processing chamber; carrying gas fromthe gas source to the substrate processing chamber via the gas tube;coupling RF power to the substrate processing chamber; providing an RFchoke; attenuating a voltage difference between the RF power source andthe gas source with the RF choke.
 16. The method of claim 15, whereinproviding an RF choke includes disposing the RF choke around the gastube.
 17. The method of claim 15, wherein providing an RF choke includesproviding a wire wrapped into a coil.
 18. The method of claim 17,wherein providing a wire wrapped into a coil includes disposing the wirearound the gas tube.
 19. The method of claim 18, wherein disposing thewire around the gas tube further includes ensuring the pitch of the wireis substantially constant.
 20. The method of claim 15, wherein providinga gas tube includes providing dielectric material.
 21. The method ofclaim 20, wherein providing the RF choke includes providing a wirewrapped into a coil.
 22. The method of claim 21, wherein providing awire wrapped into a coil includes disposing the wire around the gastube.
 23. The method of claim 22, wherein disposing the wire around thegas tube further includes ensuring the pitch of the wire issubstantially constant.
 24. The method of claim 17, wherein providing awire wrapped into a coil includes providing a wire coated withdielectric material.
 25. The method of claim 24, wherein providing awire coated with a dielectric material includes disposing the wirecoated with a dielectric material around the gas tube.
 26. A choke foruse with a substrate processing chamber, comprising: a wire formed intoa coil; and a form disposed inside the coil, wherein the form is adaptedto ensure the pitch of the coil is substantially constant, and whereinthe wire is coated with a dielectric material.
 27. The choke of claim26, further including a gas tube disposed inside the form.
 28. The chokeof claim 26, wherein the choke is adapted to approximately uniformlyattenuate a voltage difference between an RF power source and a gasdelivery system.